JP2018150481A - Silicone rubber composition, elastic roller and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicone rubber composition that can easily form a foam having a long pot life and including a fine cell, and an elastic roller prepared therewith.SOLUTION: The present invention provides a silicone rubber composition containing a silicone raw rubber, a crosslinker, a reaction control agent, a chemical foaming agent, and a thermally-expandable microcapsule, and an elastic roller having an elastic foamed layer containing a cured foam thereof.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a silicone rubber composition, an elastic roller, and an image forming apparatus.

  Conventionally, various elastic rollers such as a developing roller, a charging roller, a fixing roller, and a heating roller have been used in image forming apparatuses such as a printer, a copier, a facsimile machine, and a multifunction machine thereof. These elastic rollers are generally formed by forming an elastic layer including an elastic body on a shaft.

  As such an elastic roller, for example, Patent Document 1 discloses a pressure roller having characteristics of Asker C hardness of 45 degrees or more and surface micro hardness of 45 degrees or less.

JP 2000-221823 A

  In recent image forming apparatuses, finer characteristics are required by an elastic roller as the image formation becomes more precise and faster. For example, if the elastic layer of the elastic roller is formed of a foam having fine cells, energy saving can be achieved by reducing the weight of the elastic roller, lowering the thermal conductivity, and the like.

  In order to form a foamed elastic layer having fine cells (for example, an average cell diameter of 200 μm or less), a method in which a foaming agent is blended with a silicone rubber composition having a high curing speed and curing and foaming are simultaneously performed is considered. However, with this method, the pot life of the silicone rubber composition may be short, and work efficiency may be complicated, and mass production may be difficult. Further, in the above method, since the curing speed is high, it is difficult to finely adjust the expansion ratio and the cell diameter.

  One of the objects of the present invention is to provide a silicone rubber composition that has a long pot life and can easily form a foam having fine cells. Another object of the present invention is to provide an elastic roller having a foamed elastic layer formed using the silicone rubber composition, and an image forming apparatus including the elastic roller.

  One aspect of the present invention relates to a silicone rubber composition containing a silicone raw rubber, a crosslinking agent, a reaction control agent, a chemical foaming agent, and a thermally expandable microcapsule.

  Since the silicone rubber composition contains a reaction control agent, the pot life is long and the storage stability is excellent. Moreover, the said silicone rubber composition can form the foam which has a fine cell, maintaining a long pot life by using together a chemical foaming agent and a thermally expansible microcapsule. For this reason, the said silicone rubber composition can be used suitably for formation of the foaming elastic layer of an elastic roller.

  Another aspect of the present invention relates to an elastic roller comprising a shaft body and a foamed elastic layer provided on the outer peripheral surface of the shaft body, wherein the foamed elastic layer includes a foamed cured product of the silicone rubber composition. .

  In one aspect, the elastic roller may further include a coating layer provided on the foamed elastic layer.

  Still another aspect of the present invention relates to an image forming apparatus including the elastic roller.

  According to the present invention, there is provided a silicone rubber composition having a long pot life and capable of easily forming a foam having fine cells. The present invention also provides an elastic roller having a foamed elastic layer formed from the silicone rubber composition, and an image forming apparatus provided with the elastic roller.

It is a front view which shows the outline of the elastic roller which concerns on one Embodiment. It is sectional drawing which shows the cross section along the II-II line | wire of FIG. It is sectional drawing which shows the cross section along the III-III line of FIG.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that the drawings are partially exaggerated for easy understanding, and dimensional ratios and the like are not limited to those described in the drawings.

  FIG. 1 is a front view showing an outline of the elastic roller according to the present embodiment. FIG. 2 is a cross-sectional view showing a cross section taken along line II-II in FIG. 3 is a cross-sectional view showing a cross section taken along line III-III in FIG. The elastic roller 1 according to this embodiment includes a shaft body 2, a foamed elastic layer 3 provided on the outer peripheral surface of the shaft body 2, and a coating layer 4 provided on the foamed elastic layer 3. .

  The shaft body 2 may be a shaft body used for a known elastic roller. The shaft body 2 may be made of a metal such as iron, aluminum, stainless steel, or brass. Such a shaft body 2 can be rephrased as a cored bar. Moreover, the shaft body 2 is not necessarily made of metal, and may be made of, for example, a resin material. The resin material may be, for example, a thermoplastic resin or a thermosetting resin, or may be a conductive resin in which a conductivity imparting agent is blended with the thermoplastic resin or the thermosetting resin.

  The shaft body 2 may be made of a single material or may be made of two or more materials. The shaft body 2 may be composed of, for example, a core material and an outer cover layer that covers the core material. Specifically, for example, the shaft body 2 may be obtained by plating a metal core material.

  The outer peripheral surface of the shaft body 2 may be subjected to a surface roughening treatment in order to improve the adhesion to the foamed elastic layer 3 or to improve the effect of a pre-polymer treatment described later. The method for the roughening treatment is not particularly limited, and may be appropriately selected from known methods according to the material of the shaft body 2 and the like. Specific examples of the surface roughening method include sand blasting and polishing.

  The outer peripheral surface of the shaft body 2 may be subjected to a primer treatment for improving the adhesion with the foamed elastic layer 3. The method of primer treatment is not particularly limited, and may be appropriately selected from known methods according to the material of the shaft body 2, the composition of the foamed elastic layer 3, and the like. As the primer, for example, alkyd resin, modified alkyd resin such as phenol modification or silicone modification, oil-free alkyd resin, acrylic resin, silicone resin, epoxy resin, fluorine resin, phenol resin, polyamide resin, urethane resin, etc. are suitable. Can be used.

  The outer diameter of the shaft body 2 may be appropriately changed according to the form of the image forming apparatus. The outer diameter of the shaft body 2 may be, for example, 6 to 40 mm, and preferably 10 to 30 mm. The length of the shaft body 2 may be appropriately changed according to the form of the image forming apparatus. The length of the shaft body 2 may be, for example, 100 to 600 mm, and preferably 130 to 400 mm.

  The foamed elastic layer 3 is provided on the outer peripheral surface of the body portion of the shaft body 2. In the present embodiment, the foamed elastic layer 3 includes a foamed cured product of a silicone rubber composition described later.

(Silicone rubber composition)
The silicone rubber composition according to this embodiment is a composition containing a raw silicone rubber, a crosslinking agent, a reaction control agent, a chemical foaming agent, and a thermally expandable microcapsule, and is foamed and cured by heating. Thus, the composition forms a foam. Since the silicone rubber composition according to this embodiment contains a reaction control agent, the pot life is long and the storage stability is excellent. Moreover, the silicone rubber composition according to the present embodiment can form a foam having fine cells while maintaining a long pot life by using a chemical foaming agent and a thermally expandable microcapsule in combination.

  The silicone raw rubber is not particularly limited, and may be a known silicone raw rubber. Examples of the silicone raw rubber include vinyl group-containing silicone raw rubber (more specifically, for example, vinyl group-containing dimethyl silicone raw rubber, vinyl group-containing phenyl silicone raw rubber, vinyl group-containing fluorosilicone raw rubber, etc.) or modified products thereof. It is done. Moreover, a silicone raw rubber may be used individually by 1 type, and may be used in combination of 2 or more type.

  The silicone raw rubber may be, for example, millable silicone rubber, heat-crosslinking silicone rubber, or the like. As the silicone raw rubber, commercially available products may be used. For example, “KE-551U”, “KE-571-U”, “KE-1571-U”, “KE-951-U” manufactured by Shin-Etsu Chemical Co., Ltd., “KE-541-U”, “KE-551-U”, “KE-561-U”, “KE-961T-U”, “KE-1541-U”, “KE-1551-U”, “KE” -941-U "," KE-971T-U ", etc. may be used.

  The blending amount of the silicone raw rubber may be, for example, 80 to 95% by mass, and preferably 85 to 93% by mass based on the total amount of the silicone rubber composition.

  The crosslinking agent is not particularly limited, and a known crosslinking agent for silicone rubber may be used. Examples of the crosslinking agent include addition reaction crosslinking agents and organic peroxide crosslinking agents. Examples of the addition reaction crosslinking agent include organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule. The organohydrogenpolysiloxane may have, for example, a linear, cyclic or branched alkyl group. Examples of the organic peroxide crosslinking agent include benzoyl peroxide, bis-2,4-secondary chlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5- Bis (t-butylperoxy) hexane is exemplified. A crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The amount of the crosslinking agent may be, for example, 0.5 to 20% by mass based on the total amount of the silicone rubber composition, and preferably 1 to 10% by mass.

  The silicone rubber composition may further contain a curing accelerator that accelerates the reaction between the raw silicone rubber and the crosslinking agent. As a hardening accelerator, a platinum catalyst etc. are mentioned, for example. Examples of the platinum catalyst include chloroplatinic acid, alcohol-modified chloroplatinic acid, platinum supported on a solid catalyst (for example, platinum black, alumina, silica, carbon, etc.), platinum and olefin, alcohol or vinylsiloxane. Complex, and the like.

  The compounding quantity of a hardening accelerator may be 0.3-2.0 mass% on the basis of the whole quantity of a silicone rubber composition, for example, and it is preferable that it is 0.5-1.5 mass%.

  The reaction control agent is a component that suppresses the crosslinking reaction of the silicone raw rubber at room temperature (for example, 23 ° C.). The reaction control agent may be, for example, a component that is deactivated or volatilized by heating. By including the reaction control agent, the pot life of the silicone rubber composition is prolonged, and the silicone rubber composition is excellent in workability.

  The reaction control agent can be appropriately selected from components that can suppress the crosslinking reaction of the silicone raw rubber at room temperature, depending on the types of the silicone raw rubber, the crosslinking agent, and the curing accelerator blended in the silicone rubber composition. For example, when the silicone rubber composition contains a platinum catalyst as a curing accelerator, methylvinylcyclotetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, hydroperoxide, and the like can be suitably used as the reaction control agent.

  The blending amount of the reaction control agent is not particularly limited, and can be appropriately adjusted according to the desired pot life, curing temperature, curing rate, and the like. The compounding amount of the reaction control agent may be, for example, 0.5 to 8.0% by mass, preferably 1.0 to 6.0% by mass based on the total amount of the silicone rubber composition.

  The silicone rubber composition contains a chemical foaming agent and a thermally expandable microcapsule. By including both the chemical foaming agent and the thermally expandable microcapsule, the silicone rubber composition has a sufficiently small average cell diameter of the foam formed even when the curing speed is low. That is, according to the said silicone rubber composition, the foam which has a fine cell can be obtained easily.

  The chemical foaming agent may be a foaming agent that generates gas by thermal decomposition. The chemical foaming agent is not particularly limited, and a known chemical foaming agent may be used. As the chemical foaming agent, for example, organic azo foaming agents such as azobisisobutyronitrile (AIBN), azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT), hydrazodicarbonamide (HDCA) and the like are suitable. Can be used.

  The compounding quantity of a chemical foaming agent is not specifically limited, It can adjust suitably according to desired foaming ratio. The compounding quantity of a chemical foaming agent may be 0.1-5.0 mass% on the basis of the whole quantity of a silicone rubber composition, for example, and it is preferable that it is 1.2-3.0 mass%.

  The thermally expandable microcapsule may have a shell containing a high molecular component and an encapsulating agent containing a low molecular component. In such a heat-expandable microcapsule, the encapsulant is vaporized or expanded by heating, and the shell expands due to the pressure. The polymer component is not particularly limited, and may be, for example, a thermoplastic polymer. A low molecular component is not specifically limited, For example, hydrocarbons, such as butane and isobutane, may be sufficient.

  Examples of the polymer component constituting the shell (outer shell) of the thermally expandable microcapsule include thermoplastic resins such as vinylidene chloride / acrylonitrile copolymer, methyl methacrylate / acrylonitrile copolymer, and methacrylonitrile / acrylonitrile copolymer. Is mentioned. The thermally expandable microcapsule desirably expands at least at a temperature at which the silicone rubber composition is cured. Therefore, as the thermally expandable microcapsule, a thermally expandable microcapsule in which the softening temperature of the resin constituting the shell is within an appropriate range may be appropriately selected according to the curing temperature of the silicone rubber composition.

  The compounding amount of the thermally expandable microcapsule is preferably 20 parts by mass or more and more preferably 100 parts by mass or more with respect to 100 parts by mass of the chemical foaming agent. Moreover, the compounding quantity of a thermally expansible microcapsule may be 500 mass parts or less with respect to 100 mass parts of compounding quantities of a chemical foaming agent, and it is preferable that it is 400 mass parts or less.

  The compounding quantity of a thermally expansible microcapsule is not specifically limited, It can adjust suitably according to a desired expansion ratio. The compounding amount of the thermally expandable microcapsule may be, for example, 0.1 to 5.0% by mass based on the total amount of the silicone rubber composition, and preferably 0.5 to 2.5% by mass.

  The silicone rubber composition may further contain components other than those described above. For example, the silicone rubber composition may further contain a reinforcing silica filler such as fumed silica and precipitated silica. The silicone rubber composition may further contain a curing aid. The curing aid may be a peroxide, for example. Peroxides include benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butyl peroxide). Examples thereof include oxy) hexane and the like.

  The silicone composition may further contain a heat resistance improver, non-reinforcing silica for adjusting hardness, a filler, a colorant, a thermal conductivity improver, and the like.

  The foamed elastic layer 3 may be formed by heating and foaming and curing a silicone rubber composition disposed on the outer peripheral surface of the shaft body 2. That is, the foamed elastic layer 3 may be composed of a foamed cured product of a silicone rubber composition. The curing temperature may be, for example, 100 to 300 ° C or 150 to 270 ° C.

  The foamed elastic layer 3 may be formed by grinding or polishing a foamed cured product of the silicone rubber composition formed on the outer peripheral surface of the shaft body 2 to have a predetermined thickness. The grinding or polishing may be, for example, external grinding with a cylindrical grinder.

  The foamed cured product of the silicone rubber composition is desirably a foam having fine cells. The foamed cured product preferably has fine cells having an average cell diameter of 200 μm or less, and more preferably has fine cells having an average cell diameter of 150 μm or less. Moreover, the average cell diameter of the fine cell which a foaming cured material has may be 10 micrometers or more, for example, and may be 100 micrometers or more.

  In addition, in this specification, the average cell diameter of the fine cell which a foaming cured material has is measured with the following method. That is, the cut surface of the foamed cured product was observed by magnifying it to 50 to 200 times with an optical microscope, and the cell diameter (maximum cell diameter) was measured for 10 randomly selected cells. The average cell diameter can be obtained by calculating the average value.

  The thickness of the foamed elastic layer 3 may be appropriately set according to the use of the elastic roller 1 or the like. For example, the thickness of the foamed elastic layer 3 may be 1 mm or more, and may be 4 mm or more. The thickness of the foamed elastic layer 3 may be, for example, 20 mm or less, or 10 mm or less.

  A covering layer 4 may be provided on the outer peripheral surface of the foamed elastic layer 3. The coating layer 4 is a layer that covers the outer peripheral surface of the foamed elastic layer 3 and flattens the roller surface.

  The composition of the coating layer 4 may be appropriately selected according to the use of the elastic roller. For example, the coating layer 4 may be a layer containing a fluororesin (fluororesin layer).

  Examples of the fluororesin include fluorinated ethylene-propylene copolymer (FEP), fluorinated ethylene-perfluoroalkyl vinyl ether copolymer (PFA), and polytetrafluoroethylene (PTFE).

  The thickness of the coating layer 4 is not particularly limited, and may be appropriately adjusted according to the type of the coating layer 4 and the use of the elastic roller 1. The thickness of the coating layer 4 may be 20 to 150 μm, for example, and may be 25 to 120 μm.

  Between the foamed elastic layer 3 and the coating layer 4, an adhesive layer for bonding them may be further provided. The adhesive layer may be a layer containing an adhesive or a cured product thereof. As the adhesive, for example, a silicone adhesive, an acrylic adhesive, or the like can be used. The thickness of an adhesive bond layer is not specifically limited, For example, it may be 1-100 micrometers and may be 5-50 micrometers.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, one aspect of the present invention relates to an image forming apparatus including the elastic roller 1. In the image forming apparatus, the elastic roller 1 is used as, for example, a pressure roller or a fixing roller. The components other than the elastic roller 1 in the image forming apparatus may be the same as those in the known image forming apparatus.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to an Example.

In the examples and comparative examples, the following raw materials were used.
Silicone raw rubber: Trade name “KE-551U”, manufactured by Shin-Etsu Chemical Co., Ltd., millable silicone rubber.
Addition crosslinking agent: trade name “C-25B”, manufactured by Shin-Etsu Chemical Co., Ltd.
Organic peroxide cross-linking agent: trade name “C-3”, manufactured by Shin-Etsu Chemical Co., Ltd.
Platinum catalyst: trade name “C-25A”, manufactured by Shin-Etsu Chemical Co., Ltd.
-Chemical foaming agent: Azobisisobutyronitrile (AIBN), manufactured by Otsuka Chemical Co., Ltd.
-Thermally expandable microcapsule: Trade name “Matsumoto Microsphere”, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.

Example 1
In Example 1, 100 parts by mass of a millable silicone rubber, 2.0 parts by mass of an addition crosslinking agent, 2.0 parts by mass of an organic peroxide crosslinking agent, 1.5 parts by mass of a platinum catalyst, and 1.5 parts by mass of a reaction control agent Then, 1.0 part by mass of a chemical foaming agent (AIBN) and 1.0 part by mass of thermally expandable microcapsules were mixed to prepare a silicone rubber composition (A-1).

  30 minutes after the preparation, when the silicone rubber composition (A-1) was measured with a plasticity meter, the plasticity was 220. From this, it was confirmed that the silicone rubber composition (A-1) has a sufficiently long pot life.

  Next, a metal shaft body (shaft body obtained by electroless nickel plating on SUM22, diameter: 18.0 mm) was washed with toluene and coated with a primer. The primer was applied, and the metal shaft was baked in a gear oven at a temperature of 180 ° C. for 30 minutes and cooled at room temperature for 30 minutes or more. Next, the metal shaft body and the silicone rubber composition (A-1) are integrally extruded by an extruder, and this is heated to 220 ° C. in an IR furnace to obtain the silicone rubber composition (A-1). Was foamed and cured. Thereafter, external grinding was performed with a cylindrical grinder to form a foamed elastic layer having a thickness of 6.0 mm.

  Next, an adhesive was applied to the outer peripheral surface of the foamed elastic layer, and this was pressed into a 50 μm thick PFA tube and heated at a temperature of 120 ° C. for 1 hour to form a coating layer made of PFA. The elastic roller (A-1) of Example 1 was obtained by the above method.

  About the obtained elastic roller (A-1), when the average cell diameter of the fine cell which a foaming elastic layer has was measured, the average cell diameter was 80 micrometers.

(Example 2)
A silicone rubber composition (A-2) was prepared in the same manner as in Example 1 except that the amount of the thermally expandable microcapsule was changed to 0.2 parts by mass. With respect to the obtained silicone rubber composition (A-2), the plasticity after 30 minutes was measured in the same manner as in Example 1. The plasticity was 250. From this, it was confirmed that the silicone rubber composition (A-2) has a sufficiently long pot life.

  Next, an elastic roller (A-2) was produced in the same manner as in Example 1 except that the silicone rubber composition (A-2) was used instead of the silicone rubber composition (A-1). About the obtained elastic roller, when the average cell diameter of the fine cell which a foaming elastic layer has was measured, the average cell diameter was 150 micrometers.

(Example 3)
A silicone rubber composition (A-3) was prepared in the same manner as in Example 1 except that the amount of the thermally expandable microcapsule was changed to 2 parts by mass. With respect to the obtained silicone rubber composition (A-3), the plasticity after 30 minutes was measured in the same manner as in Example 1. As a result, the plasticity was 220. From this, it was confirmed that the silicone rubber composition (A-3) has a sufficiently long pot life.

  Next, an elastic roller (A-3) was produced in the same manner as in Example 1 except that the silicone rubber composition (A-3) was used instead of the silicone rubber composition (A-1). About the obtained elastic roller, when the average cell diameter of the fine cell which a foaming elastic layer has was measured, the average cell diameter was 80 micrometers.

(Example 4)
A silicone rubber composition (A-4) was prepared in the same manner as in Example 1 except that the amount of the reaction control agent was changed to 0.2 parts by mass. With respect to the obtained silicone rubber composition (A-4), the plasticity after 30 minutes was measured in the same manner as in Example 1. The plasticity was 300. From this, it was confirmed that the silicone rubber composition (A-4) has a sufficiently long pot life.

  Next, an elastic roller (A-4) was produced in the same manner as in Example 1 except that the silicone rubber composition (A-4) was used instead of the silicone rubber composition (A-1). About the obtained elastic roller, when the average cell diameter of the fine cell which a foaming elastic layer has was measured, the average cell diameter was 220 micrometers.

(Example 5)
A silicone rubber composition (A-5) was prepared in the same manner as in Example 1 except that the amount of the thermally expandable microcapsule was changed to 4 parts by mass. With respect to the obtained silicone rubber composition (A-5), the plasticity after 30 minutes was measured in the same manner as in Example 1. The plasticity was 220. From this, it was confirmed that the silicone rubber composition (A-5) has a sufficiently long pot life.

  Next, an elastic roller (A-5) was produced in the same manner as in Example 1 except that the silicone rubber composition (A-5) was used instead of the silicone rubber composition (A-1). About the obtained elastic roller, when the average cell diameter of the fine cell which a foaming elastic layer has was measured, the average cell diameter was 80 micrometers.

(Comparative Example 1)
A silicone rubber composition (B-1) was prepared in the same manner as in Example 1 except that the thermally expandable microcapsules were not blended. With respect to the obtained silicone rubber composition (B-1), the plasticity after 30 minutes was measured in the same manner as in Example 1. As a result, the plasticity was 220.

  Next, an elastic roller (B-1) was produced in the same manner as in Example 1 except that the silicone rubber composition (B-1) was used instead of the silicone rubber composition (A-1). About the obtained elastic roller, when the average cell diameter of the fine cell which a foaming elastic layer has was measured, the average cell diameter was 300 micrometers.

(Comparative Example 2)
A silicone rubber composition (B-2) was prepared in the same manner as in Example 1 except that neither the reaction control agent nor the thermally expandable microcapsule was blended. With respect to the obtained silicone rubber composition (B-2), the plasticity after 30 minutes was measured in the same manner as in Example 1. The plasticity was 350. From this, it was confirmed that the pot life of the silicone rubber composition (B-2) was remarkably short compared with the Examples.

  Next, an elastic roller (B-2) was produced in the same manner as in Example 1 except that the silicone rubber composition (B-2) was used in place of the silicone rubber composition (A-1). About the obtained elastic roller, when the average cell diameter of the fine cell which a foaming elastic layer has was measured, the average cell diameter was 120 micrometers.

  DESCRIPTION OF SYMBOLS 1 ... Elastic roller, 2 ... Shaft body, 3 ... Foam elastic layer, 4 ... Covering layer.

Claims (4)

Silicone raw rubber,
A crosslinking agent;
A reaction control agent;
Chemical foaming agents,
Thermally expandable microcapsules;
A silicone rubber composition containing A shaft body;
A foamed elastic layer provided on the outer peripheral surface of the shaft body;
With
The elastic roller in which the said foaming elastic layer contains the foaming hardened | cured material of the silicone rubber composition of Claim 1.   The elastic roller according to claim 2, further comprising a coating layer provided on the foamed elastic layer.   An image forming apparatus comprising the elastic roller according to claim 2.

Images